No worries, I'm with you - I missed a scene with Shuu and an adorable cat, and every day I think about going back and playing it through just to get that scene, lol.
It was definitely after the fan meeting with Tocchan as your lover - just went back and checked my save. I too was the subbiest of bottoms, at that point having 0% in-charge and 0% top. It happens after the meeting - you demand a reward for your good behavior, and the reward you want is office sex. As you do. :D